1. Field of the Invention
This invention relates to RF (radio frequency) detector circuits.
The invention has a particular application for use in RF power control loops such as are utilized in RF transmitters for transmitting RF signals.
2. Description of the Related Art
The use of a diode provides a simple means for detecting RF signals. However such a detector has the disadvantage that its response tends to vary with changes in ambient temperature.
UK Patent Application No. 2 276 992 discloses detecting circuitry for detecting RF signals, including a first current source for generating a first current, a first current mirror device coupled to the first current source for producing a first mirror current, and a rectifying circuit biased on the first mirror current and rectifying RF signals to produce an output signal. The first current source generates a first current having a positive temperature coefficient of change with temperature; a second source generates a second current having a negative coefficient of change with temperature; and a second current mirror device combines the first and second currents to produce a second mirror current which is coupled to the first current mirror device. This known detector circuit compensates for temperature variations, but is of complex and expensive construction.